1. Field of the Invention
The present invention relates to the provision of a visual warning of the presence of a public safety vehicle to traffic which is following or overtaking that vehicle and, particularly, to improvements in and to warning light systems for employment on emergency vehicles. More specifically, this invention is directed to a rear-facing light bar, which spans substantially the entire width of a vehicle and includes a plurality of individually controllable light sources, and especially to a light bar which does not significantly increase the overall height or wind resistance of a vehicle on which it is installed. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
Attention attracting systems for increasing the visibility of police and other public service vehicles have long been known in the art. The most widely employed type of emergency vehicle visual warning system is the light bar. A typical light bar, as exemplified by the disclosures of U.S. Pat. Nos. 4,620,268 and 5,027,260, includes a plurality of light generators arranged on a support which spans from side-to-side, and either rests on or is spaced slightly above, the roof of the emergency vehicle. Light bars have the desirable ability to produce a wide variety of highly visible light radiation patterns. A light bar, however, possesses certain inherent disadvantages. Firstly, prior art light bars increase vehicle wind resistance and thus increase fuel consumption. Also, because of the turbulence created thereby, a conventional light bar will cause at least some increase in the ambient noise level and will thus have a negative effect on communications. Further, a light bar will increase vehicle height and this, in turn, may limit access to certain areas and/or present the possibility of damage to the light bar or property in situations where there is reduced overhead clearance. Perhaps most importantly, a light bar is a conspicuous addition to a vehicle and there are many situations where a law enforcement official does not wish his or her presence to be "announced" by a roof-mounted object, i.e., a light bar, when the warning lights on the vehicle are not energized.
The warning lights on an emergency vehicle, when energized, must unambiguously convey knowledge of the presence of that vehicle to on-coming traffic, to traffic being overtaken, to traffic approaching from the side at an intersection and to traffic which is following and/or overtaking the emergency vehicle, particularly when it is stopped. A light bar, because of its ability to project pulses of light which are directed forwardly, rearwardly and to the side of the vehicle on which it is installed, provides all of the necessary directional warnings. However, the warning of on-coming traffic and traffic which is being overtaken, as well as the warning of traffic which is moving at an acute or right angle to the path of an emergency vehicle, can be effectively accomplished by various combinations of grill or bumper mounted warning lights, headlight flashers, warning lights mounted inside the vehicle on the dash board, sun visors or rear-vision mirror and warning lights integrated with the externally mounted rear view mirrors such as disclosed in U.S. Pat. No. 5,660,457.
It is well known that traffic which is overtaking an emergency vehicle, particularly when the emergency vehicle is stationary, presents the greatest danger for a collision. Tail/back-up light flashers and rear bumper mounted warning lights, in part because such lights are located relatively close to the ground, do not provide as effective a warning to such overtaking traffic as is afforded by a conventional roof-mounted light bar. Additionally, such individual lights, even when operated in combination, do not have either the attention-attracting capability of or the ability to convey directional information possessed by a light bar which may house eight or more separately controllable high intensity light generators.
To summarize the foregoing discussion, there has been an unsatisfied demand for a rear-facing warning light system which would possess all of the advantages of the conventional light bar without the above-discussed disadvantages thereof.